Map Skew Integration

Integrates map skew lookup based on shapefile & tiffs provided by USGS. If user selects "map skew" in station specifications RHOT, the app auto-populates the skew and standard error values in the table based on the latitude and longitude.

App alerts user is lat/long are missing or if they do not correspond with a skew value in the geospatial data.

Known issue where making changes too fast in station specifications RHOT causes improper handling - if the last change has not fully rendered before the next is made, the second change may be erased once the rendering for the first task completes. I've working to make the computation more efficient to reduce the risk of this occurring. This merge does fix some other prior issues with station specs RHOT handling.

Ready to merge after review by Shanna. Okay to delete source branch once merged.